Election beam exposure system and an apparatus for carrying out a pattern unwinder

Abstract

In an electron beam system in which the beam is exposed in selected prescribed patterns on a target surface, stored pattern data specifies the location of the pattern as coordinates on the target plane of a reference point in the pattern, specifies the shape of the pattern as a code identifying one of several permissible shapes, and specifies the size of the pattern as dimensions of first and second pattern dimensions in the target plane. In exposing each pattern, the data is: modified to provide the selected pattern in the desired size; modified to determine the maximum beam size for the selected pattern; dynamically fragmented into individual beam flashes; and examined to determine the beam spot size, shape and position for each flash. All patterns are generally designated as trapezoids, with a triangle considered as a trapezoid having one side of zero length, a rectangle considered as a trapezoid having four right angles, etc.

what is claimed is: 
     
       1. A method of exposing a predetermined pattern at a target plane to an electron beam that is momentarily flashed on at each of plural exposure locations within the predetermined pattern until the predetermined pattern is entirely exposed, said method comprising the steps of: (a) storing pattern data representing said predetermined pattern, said pattern data specifying the location, size and shape of the predetermined pattern on the target plane;   (b) in response to the pattern data for said predetermined pattern, determining the beam spot sizes, shaped and exposure locations on the target plane required to expose the predetermined pattern;   (c) sequentially deflecting the electron beam to each of said exposure locations in turn; and   (d) at each exposure location attained in step (c), momentarily exposing the beam on said target surface and shaping the beam top expose only the beam spot shape determined in step (b) for that exposure location.   
     
     
       2. The method according to claim 1 wherein step (b) includes the step of minimizing the number of exposure locations required to expose the predetermined pattern by determining the maximum permissible beam spot size that can be exposed at each exposure location. 
     
     
       3. The method according to claim 2 wherein step (a) includes the steps of: (a.1) specifying the location of said predetermined pattern as the coordinates on the target plane of a reference point in the predetermined pattern;   (a.2) specifying the shape of the predetermined pattern as a code identifying one of several permissible pattern shapes; and   (a.3) specifying the size of the predetermined pattern as first and second pattern dimensions in the target plane.   
     
     
       4. The method according to claim 3 wherein step (d) includes the step of shaping the beam, for each momentary beam exposure, to alternatively define triangular and rectangular beam profiles. 
     
     
       5. The method according to claim 3 wherein step (c) comprises the steps of: (c.1) initially deflecting the electron beam to a reference location along the border of the predetermined pattern;   (c.2) deflecting the beam to successive adjacent locations along the border of the predetermined pattern until the entire border of the predetermined pattern has been exposed; and   (c.3) after the border of the predetermined pattern has been exposed, deflecting the beam to successive adjacent locations within the border in accordance with a prescribed sequential directional protocol until the entire prescribed pattern has been exposed;   and wherein step (d) includes the steps of momentarily exposing the beam on said target surface at each of the deflected locations of steps (c.1), (c.2), and (c.3).   
     
     
       6. The method according to claim 5 wherein step (b) comprises the step of establishing the size of said beam spot as first and second beam spot dimensions in accordance with said first and second pattern dimensions, respectively. 
     
     
       7. The method according to claim 5 wherein the shape and size of the beam are adjustable at each individual exposure location attained in step (c). 
     
     
       8. The method according to claim 3 wherein step (b) comprises the step of establishing the size of said beam spot as first and second beam spot dimensions in accordance with the first and second pattern dimensions, respectively. 
     
     
       9. The method according to claim 1 wherein step (c) comprises the steps of: (c.1) initially deflecting the electron beam to a reference location along the border of the predetermined pattern;   (c.2) deflecting the beam to successive adjacent locations along the border of the predetermined pattern until the entire border of the predetermined pattern has been exposed; and   (c.3) after the order of the predetermined pattern has been exposed, deflecting the beam to successive adjacent locations within the border in accordance with a prescribed sequential directional protocol until the entire prescribed pattern has been exposed;   and wherein step (d) includes the steps of momentarily exposing the beam on said target surface at each of the deflected locations of steps (c.1), (c.2), and (c.3).   
     
     
       10. The method according to claim 1 wherein the shape and size of the beam are adjustable at each individual exposure location attained in step (c). 
     
     
       11. Apparatus for exposing a predetermined pattern in a target plane to an electron beams, said apparatus comprising: selectively actuable flash generator means for momentarily emitting an electron beam generally toward said target plane;   storage means for storing pattern data representing the size, shape and location of said predetermined pattern on the target plane;   control means responsive to the stored pattern data for establishing beam spot sizes, shapes and exposure locations on the target plane required to expose the predetermined pattern;   deflection means for sequentially deflecting said beam to each of said exposure locations in turn;   actuator means for actuating said flash generator means momentarily at each of said exposure locations; and   shaping means for shaping the beam at each of said exposure locations in accordance with the beam spot shape established for that exposure location by said control means.   
     
     
       12. The apparatus according to claim 11 wherein step deflection means comprises: means for initially deflecting the electron beam to a reference location along the border of the predetermined pattern;   means for deflecting the electron beam to successive adjacent locations along the bore of the predetermined pattern until the beam spot has been sequentially positioned along the entire border; and   means responsive to sequential positioning of the electron beam spot along the entire border for deflecting the electron beam to successive adjacent locations within the border in accordance with a prescribed sequential directional protocol until the electron beam spot has been positioned to fill in the entire predetermined pattern.   
     
     
       13. The apparatus according to claim 11 wherein said storage means includes means for storing said pattern data in a plurality of segments, a first of said segments specifying the location of the predetermined pattern as the coordinates on the target plane of a reference point in the predetermined pattern; a second of said segments specifying the shape of said predetermined pattern as a code representing one of several permissible pattern shapes, and a third of said segments specifying the size of said predetermined pattern as first and second pattern dimensions in the target plane. 
     
     
       14. The apparatus according to claim 13 wherein said control means comprises means for establishing the size of said beam spot as first and second beam spot dimensions as a function of said first and second pattern dimensions, respectively. 
     
     
       15. The apparatus according to claim 11 wherein said control means comprises means for minimizing the number of exposure locations required to expose the predetermined pattern in said target plane, said means for minimizing comprising means for determining the maximum permissible beam spot size that can be exposed at each of said exposure locations.